What are two advantages of having the encyclopedia stored on CD-ROM?

As opposed to having it in book form

1. Encyclopedia is searchable, with a few key presses one could easily browse a list of all articles pertaining to the desired subject.

2. Portable. A good quality 'dead-tree' printed encyclopedia consists of up to 40 or 50 large hard-bound books. Not exactly something you can take with you.

As opposed to having it online

1. No internet required to use it.

2. Entries with audio or video will load much faster and more reliably.